Certain substituted heterocycle fused gamma-carbolines have been reported to be agonists or antagonists of 5-HT2 receptors, particularly 5-HT2A and 5-HT2c receptors, in treating central nervous system disorders. These compounds have been disclosed in U.S. Pat. Nos. 6,548,493; 7,238,690; 6,552,017; 6,713,471; 7,183,282; U.S. RE39680, and U.S. RE39679, as novel compounds useful for the treatment of disorders associated with 5-HT2A receptor modulation such as obesity, anxiety, depression, psychosis, schizophrenia, sleep disorders, sexual disorders migraine, conditions associated with cephalic pain, social phobias, gastrointestinal disorders such as dysfunction of the gastrointestinal tract motility, and obesity. PCT/US08/03340 (WO 2008/112280) and U.S. application Ser. No. 10/786,935 (U.S. Pub. No. 2004/0209864) also disclose methods of making substituted heterocycle fused gamma-carbolines and uses of these gamma-carbolines as serotonin agonists and antagonists useful for the control and prevention of central nervous system disorders such as addictive behavior and sleep disorders. WO 2009/114181 also discloses of methods of preparing toluenesulfonic acid addition salt crystals of these substituted heterocycle fused gamma-carbolines.
In addition, WO/2009/145900 discloses use of particular substituted heterocycle fused gamma-carbolines for the treatment of a combination of psychosis and depressive disorders as well as sleep, depressive and/or mood disorders in patients with psychosis or Parkinson's disease. In addition to disorders associated with psychosis and/or depression, this patent application discloses and claims use of these compounds at a low dose to selectively antagonize 5-HT2A receptors without affecting or minimally affecting dopamine D2 receptors, thereby useful for the treatment of sleep disorders without the side effects of the dopamine D2 pathways or side effects of other pathways (e.g., GABAA receptors) associated with convention sedative-hypnotic agents (e.g., benzodiazepines) including but not limited to the development of drug dependency, muscle hypotonia, weakness, headache, blurred vision, vertigo, nausea, vomiting, epigastric distress, diarrhea, joint pains, and chest pains.
While these substituted heterocycle fused gamma-carbolines and their uses have been reported, particularly for the treatment of diseases such as schizophrenia, patient compliance in adhering to the medication schedule is a common and critical problem in therapy. According to one study, non-compliance with antipsychotic medication is observed in around 50% of people with schizophrenia. Such non-compliance is linked to the increase in re-hospitalizations and generally poorer outcome in people with psychotic disorders. Therefore, there exists a need for drugs, particularly anti-psychotic drugs that can overcome the non-compliance and provide prodrugs which have a sustained or delayed release profile.